Sex differences in extracellular and intracellular calcium-mediated vascular reactivity to vasopressin in rat aorta

• Published in: European journal of pharmacology 1998-11, Vol.361 (2), p.207-216
• Main Authors: Eatman, Danita, Stallone, John N., Rutecki, Gregory W., Whittier, Frederick C.
• Format: Article
• Language: English
• Subjects: 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester - pharmacology; Animals; Aorta - drug effects; Aorta - metabolism; Biological and medical sciences; Blood vessels and receptors; Calcium; Calcium - metabolism; Calcium Channel Agonists - pharmacology; Calcium Channel Blockers - pharmacology; Diltiazem; Diltiazem - pharmacology; Dose-Response Relationship, Drug; Female; Fundamental and applied biological sciences. Psychology; Hormones and neuropeptides. Regulation; Hypothalamus. Hypophysis. Epiphysis. Urophysis; In Vitro Techniques; Male; Potassium Chloride - pharmacology; Rat; Rats; Rats, Sprague-Dawley; Sex Characteristics; Sexual dimorphism; Simvastatin; Simvastatin - pharmacology; Vasoconstriction - drug effects; Vasopressin; Vasopressins - metabolism; Vertebrates: cardiovascular system; Vertebrates: endocrinology
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/S0014-2999(98)00700-6

In rat thoracic aorta, contractile responses to arginine vasopressin are two-fold higher in females than in males. To determine the roles of extracellular and intracellular Ca 2+ in this sexual dimorphism in vascular function, vascular reactivity and Ca 2+ channel function were examined in thoracic aortae of male and female rats. In the presence of diltiazem (10 μM), maximal contraction to vasopressin was reduced to a greater extent in male (65±2%) than in female aortae (38±1%). Maximal contractile responses to KCl and Bay K 8644 were similar in male and female aortae. Sensitivity to KCl was slightly but significantly higher in male than in female aorta; in contrast, sensitivity to Bay K 8644 was nearly three-fold higher in males than in females. Removal of the endothelium enhanced sensitivity to KCl similarly in male and female aortae. In the presence of simvastatin (60 μM; an inhibitor of intracellular Ca 2+ release), reactivity to vasopressin was reduced substantially in female (42±1%) but unaltered in male aortae. Removal of the endothelium enhanced the inhibitory effect of simvastatin in both female (73±2%) and male aortae (41±2%). These findings demonstrate that male aortae depend more upon extracellular Ca 2+ influx, whereas female aortae depend more upon intracellular Ca 2+ release for vasopressin-induced contraction.